Electric circuit interrupter



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Patented Oct. 29, 1935 PATENT OFFICE 2,019,348 ELECTRIC CIRCUITINTERRUPTER Leland S. Hobson, Yeadon, Pa., assignor to General ElectricCompany, a corporation of New York Application September I, 1934, SerialNo. 743,109

6 Claims.

My invention relates to electric circuit interrupters of the fluid-blasttype and has for its principal object the provision of an improvedcircuit interrupter of the aforesaid type particularly adapted to theuse of an arc-extinguishing liquid, as water, which is partiallyconducting as contrasted with the usual circuit breaker oil.

The use of a readily vaporizable and non-inflammable arc-extinguishingliquid, as water, in

electric circuit interrupters has a number of advantages includingpractically instantaneous generation of adequate blast pressure uponopening of the circuit, elimination of fire hazard and decreased cost.In accordance with my invention,

an electric circuit interrupter is provided with an explosion potcontaining an arc-extinguishing liquid of the character above referredto, and the explosion pct which forms a part of the movable contactstructure is positioned above the level of a. separate body of similararc-extinguishing liquid in the closed circuit position and arranged tobe lowered into said liquid for refilling by and in accordance with thecircuit opening operation.

My invention will be more fully set forth in the following descriptionreferring to the accompanying drawing, and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to 80' and forming a part of this specification.

Referring to the drawing, the single figure thereof is an elevationalview, partly in section, of an electric circuit interrupter of thefluidblast type embodying my invention.

35 The circuit interrupter illustrated comprises a main tank or casing Icontaining a suitable arcextinguishing liquid 2, as water. Relative-1ymovable contact structure for interrupting the circuit is disposedwithin the tank and in the closed circuit position shown is disposed inthe gas or air space above the level of the liquid 2.

The aforesaid contact structure comprises a pair of fixed contacts 3mounted at the lower ends 45 0f the conventional lead-in bushings 4 anda conducting bridging member 5 arranged to engage and interconnect thefixed contacts 3 in the closed circuit position.

The movable contact structure, in addition to 50 the bridging member 5,comprises an explosion pot 6 of insulating material formed in thepresent instance as a cylinder or tube closed at its opposite ends andenclosing the bridging member 5. The explosion pot 6 is provided at itsupper 85 side with apertures 1 for receiving the fixed con tacts 3 andfor serving as the usual blast openings during circuit interruption.

The explosion pot 6 when in the closed circuit position shown likewisecontains an arc-extinguishing liquid 2' similar to that in the tank 5'so that upon lowering of the movable contact structure, as by the usualoperating or lift rod 8, the arcs formed on separation of the contacts 3and 5 instantly vaporize a portion of the liquid and generate highpressure within the explosion i pot. As the contacts 3 pass through theexhaust openings 1 the pressure within the explosion pot is effective todirect arc-extinguishing blasts of steam and of liquid through the arcs,causing interruption of the same. 15

In operation, the circuit is opened by lowering of the movable contactstructure into the liquid 2 at the lower part of the main tank. Arcingis interrupted by the explosion chamber effect above described. After asingle circuit interrupting 20 operation, particularly in case ofcurrents of larger magnitude, an appreciable part of thearc-extinguishing liquid within the explosion pot 6 has been ejected inthe form of vapor and atomized liquid. By immersing the explosion 25 pct6 within the liquid 2 at the end of each circuit opening operation, theexplosion pot is automatically refilled so as to be in readiness foranother circuit interrupting operation immediately after reclosure.

For the purpose of limiting the arcing pressure within the explosionpot, as during'the interruption of short circuit currents, pressurerelief means may be provided. In the arrangement shown the opposite endsof the explosion pot 6 are normally closed by valves 9 biased intoseating engagement with the ends of the insulating cylinder by springsl0. Each spring Ill is mounted on a valve guide rod l I secured at oneend, as at I2, to the bridging member 6 and having at its 40 free end anadjusting nut l3 for determining the opening pressure of the valve.

The operating means for the movable contact structure likewise includesan insulating barrier 14 which is formed as a plate of insulationsuitably secured to the movable contact structure intermediate the fixedcontacts 3. The insulating barrier I4 is effective to prevent arcing orflashover between the stationary contacts 3 when the circuit breaker isin open position, the stationary contacts 3 in such position beingisolated in air.

In cases where infrequent operation of the circuit breaker is required,evaporation of the arc-extinguishing liquid may be substantiallyprevented by a, very small amount of oil on the the upward movementpreviously used in circuit breakers using a conducting liquid. Thedownbreak has the aid of gravity to accelerate the moving contact.

Furthermore, throwing of! of water or steam, which might be expected inthe prior up-break types of circuit breakers using water, is hereprevented by the main tankand its insulating lining which completelyenclose the interrupting element.

It will be apparent that individual or separate explosion pots for eachpole of the breaker may be used instead of the tubular explosion potcommon to both poles, illustrated by way of example.

It should be understood that my invention is not limited to specificdetails 01' construction and arrangement thereof herein illustrated, andthat changes and modifications may occur to one skilled in the artwithout departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent oi the UnitedStates is:

1. An electric circuit interrupter oi the fluidblast type comprisingrelatively movable contact structure including a movable explosion potcontaining an arc-extinguishing liquid, the arc formed upon separationof said contact structure causing an arc-extinguishing blast from saidpot, and means for refilling said explosion pot with similar liquid byand in accordance with the circuit controlling operation, said contactstructure arranged so that the same is spaced by air in the open circuitposition.

2. An electric circuit interrupter of the fiuidblast type comprisingrelatively movable contact structure including a movable explosion potcontaining an arc-extinguishing liquid, a tank in which said contactstructure is mounted likewise containing similar liquid, said contactstructure in the closed circuit position being positioned above theliquid level in said tank, and means for refilling said explosion potwith liquid from said tank by and in accordance with the circuitcontrolling operation.

3. An electric circuit interrupter oi the fluidblast type comprising atank containing an arcextinguishing liquid, relatively movable contactstructure for coacting above the level oi. said liquid including anexplosion pot likewise containing arc-extinguishing liquid, and meansfor lowering said explosion pot in said tank for opening the circuit,said explosion pot being refilled with liquid from said tank by and inaccordance with said circuit controlling operation.

4. An electric circuit interrupter oi the fluidblast type comprising atank containing an arcextinguishing liquid, a pair 'of fixed contactsmounted in said tank, coacting movable contact structure including aconducting bridging member, a tubular insulating explosion pot movablewith .said bridging member, said explosion pot having openings forreceiving said fixed contacts and normally containing arc-extinguishingliquid, the aforesaid contact structure disposed above the level of theliquid in said tank in the closed circuit position, and means forlowering said bridging member and explosion pot for effecting thecircuit opening operation, said explosion pot being immersed in theliquid in said tank in the open circuit position.

5. An electric circuit interrupter of the fiuidblast type comprising atank containing an arcextinguishing liquid, a pair of fixed contactsmountedv in said tank, coacting movable contact structure including aconducting bridging member, a tubular explosion pot composed ofinsulation enclosing said bridging member, and pressure relief valves atopposite ends of said, explosion pot, said explosion pot normally filledwith a similar arc-extinguishing liquid and positioned together withsaid fixed contacts above the level of the liquid in said tank in theclosed circuit position, and operating means including an insulatingbarrier connected to said explosion pot between said fixed contacts forlowering saidexplosion pot and effecting a circuit opening operation,said explosion pot being immersed in the liquid in said tank so that itis refilled with liquid prior to the circuit closing operation.

6. An electric circuit interrupter comprising a tank containing aconducting arc-extinguishing liquid, fixed contact structure mountedabove the level of said liquid, coacting movable contact structureincluding an explosion pot containing a similar liquid, and means forlowering said movable contact structure into the liquid in said tankthereby effecting the circuit opening operation.

LELAND S. HOBSON.

